This is where the error is

            String[] newToken = line.split("#");

            pattern = Pattern.compile("ISBN\\x20(?=.{13}$)\\d{1,5}([- ])\\d{1,7}\\1\\d{1,6}\\1(\\d|X)$");
            Matcher matchIsbn = pattern.matcher(newToken[0]);
            pattern = Pattern.compile("[\\d]+");
            Matcher matchCopyNumber = pattern.matcher(newToken[1]);
            pattern = Pattern.compile("[\\D&&\\w]+");
            Matcher matchTitle = pattern.matcher(newToken[2]);
            pattern = Pattern.compile("[\\D&&\\w]+");
            Matcher matchAuthor = pattern.matcher(newToken[3]);
            pattern = Pattern.compile("[\\d]+");
            Matcher matchStatistics = pattern.matcher(newToken[4]);
            pattern = Pattern.compile("\\d{2}\\d{2}\\d{2}");
            Matcher matchBorrowDate = pattern.matcher(newToken[5]);
            pattern = Pattern.compile("\\d{2}\\d{2}\\d{2}");
            Matcher matchReturnDate = pattern.matcher(newToken[6]);
            pattern = Pattern.compile("[\\d]+");
            Matcher matchLibraryCardNumber = pattern.matcher(newToken[7]);

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 7
at assignment2Program1.WriteFromBookFile.main(WriteFromBookFile.java:54)
Java Result: 1

the first line read from the file only has 7 tokens, token[6]

0-321-26979-0#1#Java Software Solutions#9#080830#081130#90

Edited by: Implode on Oct 12, 2009 4:18 PM

jverd wrote:
How well do you understand Java arrays?
[http://java.sun.com/docs/books/tutorial/java/nutsandbolts/arrays.html]

The error message is pretty clear. It's telling you exactly what's wrong and exactly where. On line 54 of WriteFromBookFile.java, you're trying to access the 8th element (at index 7) of an array that has at most 7 elements (at indices 0..6).

You're assuming that split is giving you 8 or more tokens, but it's giving you 7 or fewer. So print out each of the elements of the split result.

EDIT: And from your comments, it seems that you know that, so where is the confusion? Why, if you know that there are only elements 0..6, are you trying to access index 7? And why are you surprised that it doesn't work?

Edited by: jverd on Oct 12, 2009 10:30 PM

I understand arrays, but I am trying to explain the following.

I need to read information from a text file.

e.g. lines in file

0-321-26979-9#4#Java Software Solutions#9#071002#071423#26
0-13-089496-6#2#Business and information systems#Nickerson#15#000506
0-13-089496-6#4#Business and information systems#Nickerson#15#000506#081109#92

Each can have a possible 8 fields.

Most of the lines don't, which is giving an array out of bounds error.

That is what I would like to know, how can it be coded so that if there arent all the fields in a line, it moves to the next.

A few more problems arise.

Firstly, some of the information spans over 2 lines, so I cannot use nextLine().
Secondly, different "lines" contain different fields. which means that i.e. token 4 in line 3 will be a different field to token 4 in line 6.

It seems like the only way to correctly check each "group" of fields , is to check if the first token contains a 0 at the first char. but that doesnt solve the fact that different lines have fields in different position, so it cannot be matched?

Does this make sense now?